Method of hardening.



PATENTED FEB 13, 1906.

r W. E. NIGKERSON. METHOD OF HARDENING.

APPLICATION FILED 522F126, 1903.

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METHOD OF HARDENING.

APPLICATION FILED SEPT.26, 1903.

PATENTED FEB. 13, 1906.

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. UNITED STAZFES PATENT orrroir WILLIAM E. NIOKERSON, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO GILLETTE SAFETY RAZOR COMPANY, OF BOSTON, MASSAOHIL SE'ITS, A OORPORATION OF MAINE.

METHODOF HARDENENG.

Patented Feb. 13,1906;

Application filed September 26, 1903. Serial No. 174,739.

' To ctZZ whom it may concern. I

Be it known that I, WILLIAM E. NICKER- soN, a citizen of the United States, and a resident ofOambrid e, in the county of Middlesex and State of Iassachusetts, have invent ed anew and useful Methodof Hardening, of which the followin is a specification.

My invention relates to the art of hard-ening steel, and is intended to provide a simple and practical method of hardening simulta- -neously and quickly a large number of thin strips or sheets of limited area.

My method has a special applicability to the hardening before sharpening of the thin flat steel blades employed in the safety-razor shown and described in United States Letters Patent No. 7 75 ,134, granted on the th day of November, 1904, on the application of King C. Gillette and will be so described herein; but my invention is not limited to such use.

In hardening steel sheets which are as thin as are the blades above referred to it is important to protect the surfaces of the sheets from contact with air while being heated, and especiall from contact with the water of the chillin ath when plun ed therein while hot, in or er to prevent the oxidation of the sheets which would result from such contacts found to be impracticable, however, for the reason that the cold liquid which isapplied to the stack comes in contact with the surface of the stack only, or, in other Words, with I the edges only of the blades, with the result that each blade has its edges or rim set while the inside portion is still very hot, and thus the hardened rim becomes slack and is caused to crinkle ,or become wa when the blade is finally cooled to a uni ofm temperature throughout, thus destroying the straightness of the edges of the blade beyond restoration and leaving the center unhardened.

According to my invention I pile a number,

of the blades ina stack; but instead of lacing them all directly in contact one wit anthemselves.

other I interleave between each few blades, and preferably between adjacent blades throughout the stack, a sheet of some metal, such as copper or silver, which is a much better conductor of heat'than is steel and has a melting-point high enough to resist the temerature to which the steel blades are heated or hardening, copper being preferred. These sheets are preferably of such size that they will project slightly beyond the edges of the adjacent blades all the way around. Th s stack of blades with the sheets interleaved is then hardened by the application of a cold liquid thereto, and the result is that the sudden change of temperature, instead of being effective at the edges or rims only of the blades, is made to occur With suflicient quickness to become effective over the entire area of the blades through the medium of the interleaved sheets, through which the heat of the blades passes away much more rapidly than it could have done through the blades This result is facilitated in case the ed es of thesheets project slightly beyond t e ed es of the blades, because the projecting e ges of the sheets in this case tend to keep the water or other liquid from circulating in direct and immediate contact with the edges of the blades and also expose a greater surface of the interleaved sheets to the action of the liquid, so that the loss of heat occurs at a practically uniform rate throughout the entire extent of each blade.

I have found that in the manner above described I can harden a large number of blades at once without causing them to lose their original flatness to any extent sufficient to interfere with their roper use.

, In hardening the lades in stacks as above described the stack of blades and interleaved sheets should be subjected to a powerful chilling action, as by the use of a current or stream of water or of a bath of ice-water or of cold brine. Afterhaving been hardened the blades are drawn to a cutting-edge temper, prefervably by means of an oil-bath at the proper temperature.

In the accompanylng drawings I have illustrated an apparatus useful in practicing my method, in -which I Figure 1 is. a front elevation of'the hardening apparatus with a portion thereof broken away. Fig. 2 is a central vertical section through the greater portion of the same viewed at right angles with respect to the position shown in Fig. 1. Fig. 3 is a detail transverse section taken on the line as :r in Fig. 2. Fig. 4 is a side elevation of a holder containing two stacks of blades, together with a frame to which the holder is temporarily secured, as hereinafter described. Fig. 5 is a section on the line y y in Fig. 4. Figs. 6 and 7 are detail views illustrating a blade and copper sheets. Fig. 8 is a detail view illustrating a latch, hereinafter described. Fig. 9 is a top plan view, and Fig. 10 is a side elevation, of the holder for the stacks of blades and coppers above referred to. Fig. 11 is a plan view of a locking-wedge, hereinafter described.

In the accompanying drawings, 2 and 3 represent two tanks located one above another, means being preferably provided for pumping water from the lower tank to the upper tank, such as pipes 4 and 5, leading througha pump 6. From the lower portion of the upper tank 2 leads a large pipe 7, provided with a valve 8, this pipe and the tank above it being shown as supported by a strong bracket 9, which may be bolted to the wall of a room and to which said pipe 7 is clamped. The lower tank 3 is assumed to stand directly upon the floor, and within the tank is located a supporting-bracket 10, carrying a pair of laterally-extending hollow heads 11. These heads may be cast in one piece, and the channels 12, provided by their hollow interiors, diver e from a central chamber 13, into whichdeads the lower end of the pipe 7, opposite the inner ends of the channels 12, which thus form outlets for any water which may descend through the pipe 7 from the upper tank 2. Guiding-rods 14 and 15 extend vertically upward from the support 10 to an arm 16, forming a part of the bracket 9, and on these guide-rods is mounted to slide a frame 17, which is represented as rectangular, thus providing a central open portion 18. This frame is connected with a weight 19 through the medium of a cord 20, passing over a pulley 21, by which weight said frame is slightly overbalanced when empty. The valve 8 is provided with suitable operating means, such as a lever 22, pivoted at the top of the tank 2 and connected at one end with the valve by a rod 23 and also provided at its other end with a depending rod 24, on which a collar 25 is rigidly clam ed. This collar carries one or more weig ts 26, the effect of which is sufficient to lift and open the valve 8 when such movement is permitted. For holding the valve closed I have shown a spring-latch 27, adapted to engage a notch 28, cut in the guided lower portion of the rod 24 when the valve 8 is closed. By releasing this latch the weights 26 will be allowed to fall and open the valve 8, and to close the valve the r0d 24 is lifted by hand into the position shown in the drawings. 29 represents a holder adapted to receive a stack of blades, with or without sheets of copper or other quick conducting metal interleaved between them. This holder itself is preferably made of copper and is shown as consisting of a rectangular rim inclosing two open spaces separated by a transverse partition 30. The holder 29 is adapted to be detachably secured in the opening 18 of the frame 17, its lower end being retained therein by lugs 31 and its upper end being retained by spring-actuated latches (Best-shown in Fig. 5.) 33 represents a thin sheet-metal blade, such as is shown and described in the Letters Patent above referred to, and 34 represents sheets of copper or other metal having a high degree of heat conductivity.

In racticing my method with the apparatus a ove described the open spaces of the holder 29 are each filled with a stack comprising a number of untempered blades 33 or similar articles interleaved, respectively, be tween copper plates, such as 34. At intervals in this stack I prefer to locate steel plates 35, having considerably greater thickness than the blades, in order to prevent any possibility of all the blades being curved in the same direction by the clamping action, here inafter described, or otherwise. The blades above referred to are usually provided with three perforations, (shown in Fig. 7 and in this case the coppers 34 and the plates 35 are also provided with perforations adapted to register with the end perforations in the blades, and the entire stack is held in place in the holder 29 by means of steel pins 36 passed endwise through holes drilled in the end portions of said holder, through the perforations in the coppers, blades, and plates, and into holes drilled through the central transverse partition of the holder, as best shown in Fig. 4. It will be understood that these pins remain in place during the hardening operation and are driven outendwise when it is desired to remove the stacks. After the holder has been filled with blades and cooperating parts, as above described, the stacks are compressed, as by means of screw-bolts 37, adapted to pass through threaded perforations formed in the end portions of the holder and to bear against the plates 35,

which are preferably made to form the end plates of the corresponding stacks, and while the stacks are under compression wedges 38, Fig. 11, are driven into the spaces opened by the action of the screw-bolts 37 between the end plates and the end portions of the holder, whereupon the screw-bolts 37 are removed. The discharge-openings formed by the outer ends of the channels 12 are given such dimensions that they correspond substantially in length with the exposed ed es of the stacks in the holder 29, and the ownward movement of the frame 17 is so limited that when in its lowermost position the edges of the stacks will be directly opposite said discharge-openings, respectively. These openings are of such width as will deliver a suflicient volume of water, a width of half an inch being suflicient for the blades above referred to. The holder 29 having been filled with blades, coppers, and plates 35, as above described, the entire holder and its contents are thoroughly heated, preferably out of contact with air or in a reducing atmosphere, to a suit able temperature to produce the desired de gree of hardness. This may be done by burying the holder and contents in a quantity of carbonaceous material contained in a mufiie and then heating the muffle. Assuming the tank 2 to be filled with water, the heated against the contents of the holder 29.

holder is then immediately placed in the frame 17, as shown in Fig. 5, whereupon the combined weight of the frame and the holder and its contents will overbalance the coun terweight 19 and cause said frame and holder to descend into the lowermost position of the frame, thus bringing the edges of the hot stacks opposite the discharge-openings, respectively. The latch 27 is then immediately released, thus causing the valve 8 to open, whereupon the water in the tank 2 rushes down through the pipe 7 and out through the channels 12, from which it is forcibly projected directly y the action of this stream of water the heat of the blades is abstracted from them with suflicient rapidity and uniformity to produce a chilling effect equal to that resulting from the plunging of an individual hot blade into cold water, the heat being abstracted through the quick conducting interleaved coppers 34. Inasmuch as copper contracts more than steel. for a given drop in temperature, the

stacks in the copper-holder 29 will be somewhat compressed by the cooling of said holder, thus preventing any water from get ting between the co pers and the blades and avoiding any possib e oxidation of the latter. After the water contained in the tank 2 has been discharged through the channels 12, as above described, the frame 17 is raised to the position shown in Fig. 2, the holder 29 is removed therefrom, the screw bolts 37- are turned in sufficiently to enable the wedges 38 to be withdrawn, the ins 36 are driven out of the stacks, and the Elades and coppers are then removed and separated. v

The razor-blades above referred to are about one and three-fourths inches long and seven-eighths of an inch wide and have a thickness of about five or siX one-thousandths of an inch, and in this case it has been my edges, of said sheets practice to use for the hardening process copper sheets having a thickness of about one thirty-second of an inch and made enough larger than the blades to overlap the latter on each edge about one eighth to three-si.vteenths of an inch. For thicker blades or other articles thicker copper sheets should be used.

While the apparatus above described is a convenient and practical apparatus for use in practicing my method, yet my invention is evidently'not limited to the use of this or any other specific apparatus.

My apparatus herein described is not claimed herein, being claimed in another application filed by me on the 26th day of May, 1904, Serial No. 209,967.

I claim as my invention-- -1. The herein-described method of hardening thin steel articles which consists in in terleaving said articles with sheets of metal of relatively high heat conductivity as com pared with steel, confining said articles and sheets in a stack, heating said stack, and. subjecting the hotstack to the action of a chilling medium, substantially as described.

2. The herein-described method of hard ening thin steel articles, which consists in interleaving said articles with sheets of metal of relatively high heat conductivity, confining said articles and sheets in a stack with the edges of said sheets projecting beyond the edges of said articles, heating said stack, and subjecting the hot stack to the action of a chilling medium.

3. The herein-described method of hardening thin steel articles, which consistsin interleaving said articles with sheets of metal of relatively high heat conductivity as compared with steel, confining said articles and sheets in a stack, heating said stack and subjecting the hot stack to the action of a flow of cold liquid.

4. The herein-described method of hardening thin steel articles, which consists in interleaving said articles with sheets of metal of relatively high heat conductivity, confining said articles and sheets in a stack with the rojecting' beyond the edges of said articles, heating said stack, and subjecting the hot stack to the action of a flow of cold liquid.

In testimony whereof I have hereunto subscribed my name this 22d day of September, 1903. I

WILLIAM E. NICKERSON.

Witnesses:

E. D. CHAnwIoK, JosnrH T. BRENNAN.

ICC 

